I've got a friend in Canberra testing the desert lime for its survival in frost and dry heat; she figured it was the best option. I _believe_ it's surviving but will have to check.
I can say that the general finger limes, including the grafted ones, really don't clay soil, frost, AND dry heat. Poor things ...
My figuring is that they'll work best in pots on the sunny side of the verandah, and possibly be brought inside in winter. Otherwise, I'm really hesitant about putting any cirtus - native or exotic - in the ground in these climates.
Sorry for the belated reply!